1. Field of the Invention
The present invention relates generally to improved sheet feeding, with particular utility for document feeders or transports for sequentially feeding original document sheets. The invention serves to reduce the imparting to the sheet material being transported and handled of friction, static charge, and foreign deleterious material while substantially minimizing the burnishing of the surface of the sheet material being transported.
2. Description of the Prior Art
As xerographic and other copiers and other document handlers in general increase in speed and become more automatic in their operation, it is increasingly important to provide higher speed yet more reliable and more automatic handling of the resulting copies, in sheet material form, while at the same time maintaining the visual quality of those resulting copies.
Throughout this disclosure the term sheet is intended to refer both to individual sheets as well as to continuous web-fed media.
Standard paper guide design relies on a series of parallel in-line ribs to decrease overall friction on the sheet as it passes through the paper path. This method also ensures that a minimum of static, dirt, and moisture is transmitted from the baffle to the sheet. In most instances, these ribs are parallel to the direction of the sheet transporting path to which the sheets are confined. A patented example of a modified design in which the ribs are in a diagonal relationship with respect to the sheet feeding path is provided in commonly assigned U.S. Pat. No. 5,000,438 issued on Mar. 19, 1991 to Sardano et al. In this patented instance, apparatus is disclosed for feeding flimsy sheets of paper or the like, preferably dog-eared or curled edge original documents. To guide and flatten the non-planar edges of the sheets, the sheet feeding guide surface of the apparatus has a plurality of spaced apart and slightly vertically extending sheet-engaging ribs. These ribs are divided into two opposingly diagonal sets of plural ribs on the respective sides of the sheet feeding path, extending diagonally away from one another from the centerline of the sheet separator or feeder towards the respective outer edges of their respective side of the sheet feeding path. These diagonal ribs may have their upper surfaces in a common plane but can iron out towards their respective path sides the curled or folded corners of the sheet in that side of the path.
While this technique of using raised ribs is acceptable for most requirements, an undesirable outcome of parallel rib design is high paper surface element dwell time on a concentrated area of the rib/sheet interface. This situation may result in paper marking and rib surface wear. Paper marking becomes a larger issue with some document handling equipment when there is a requirement to accommodate coated stock papers or transparency material which are more sensitive to surface impressions caused by surface element dwell time and high concentration of pressure between the rib and sheet interface.
It was with knowledge of the foregoing state of the technology that the present invention has been conceived and is now reduced to practice.